The antenna which is the object of the invention is a helix antenna, or a spiral antenna. In the following we call it a "helix antenna", which is the term generally used in the art. The helix antenna is a well known antenna structure. The helix antenna comprises a helix which has a short central leg part, and a connector which is connected to the helix leg, e.g. by soldering. The connection between the helix and the connector is approximately in the center of the antenna structure. The structure is thus sensitive to bending, shocks and other mechanical stresses. The interior of the antenna can be supported by forming a support part within the helix. The known helix antenna is manufactured by separately injection molding its inner and outer parts, either in the same material or in different materials. The helix part is covered with an outer cover, which is made e.g. by injection molding, or with a rubber sheath which is glued on with the connection line in the upper part of the connector. The manufacture comprises several steps, and particularly sensitive steps are the soldering of the connector and helix, and the gluing of the rubber sheath.